Patent Literature 1 discloses a communication system that includes multiple communication nodes which are connected to a communication bus having a two-line configuration, in which an average voltage between two signal lines configuring the communication bus is monitored to detect disconnection of the communication bus. More specifically, when the average voltage between the signal lines becomes equal to or larger than a predetermined threshold, it is determined that a disconnection occurs in the communication bus.
Patent Literature 1 does not consider any configuration for detecting a sign of disconnection of a communication cable at all. In order to further enhance the reliability of a communication, it is preferable that a sign of disconnection of the communication cable can be detected. This is because if the sign of disconnection can be detected, it is possible to take measures such that a communication path is switched to another before the disconnection occurs.
[Patent Literature 1] JP-A-2007-306289